Electric motors and pump assemblies are generally known, for example, in DE-OS 41 18 950. The assembly described in that patent application is a motor pump assembly. The projecting end of the shaft is not supported so that the pressure forces acting on the pistons of the pump and transferred to the rotor shaft, are supported only by the main bearing. DE-OS 23 60 182 discloses that the end of the shaft projecting from the motor housing is mounted in bearings on both sides of the driving element (main bearing, pump bearing) in order to be able to sufficiently support the forces acting on the driving element.
Applying the arrangement proposed in DE-OS 23 60 182 to the arrangement according to DE-OS 41 18 930, results in an assembly with the disadvantage that the bearings are rigidly connected with the housing of the element to be driven and the function of the electric motor can only be tested when the two housings are connected.
An object of the present invention is therefore to develop the assembly in such a way that the shaft during normal operation is sufficiently supported and that a test operation (test phase) of the electric motor is possible when the housing of the motor is not connected with the housing of the element to be driven (pump housing).
For this reason the main bearing is connected with the motor housing, but abuts in radial direction essentially on the housing of the element to be driven when the two housings are coupled.
This can be achieved, on the one hand, by inserting the main bearing only in part into a recess on the motor housing and inserting it into an opposite recess of the element to be driven when coupling the two housings.
The advantage is that the bearing plate closing the motor housing and supporting the main bearing, can be made of plastic material.
During normal operation the forces acting on the main bearing will be transferred onto the housing of the element to be driven. The forces, during the test operation, are not so high so that it is sufficient when the main bearing is supported by a plastic plate.
The housing can also be provided with a recess opening towards the inside of the housing and accommodating the main bearing. This recess corresponds to a bulge towards the outside which can be inserted into the recess of the housing of the element to be driven. The result is also that the bearing forces are finally supported by the housing of the element to be driven as soon as the two housings are coupled.
An accessory bearing at the bottom of the housing of the electric motor can be provided according to the foreseen utilization.
DE 41 32 609 A1 discloses an electric motor for driving a radial piston pump, the shaft of which is supported in an electric motor housing consisting of two parts. The shaft is supported only in a one-point bearing so that the bearing has to be much larger than the nominal diameter of the shaft in order to receive the bearing forces. The electric connection components of the electric motor are led to the outside via an opening in the bowl-shaped housing of the stator (of the electric motor).
Due to the relatively large bearing, the housing collar of the two-piece housing of the electric motor is considerably longer so that the overall length and the weight cannot be reduced further. A second disadvantage results from the external arrangement of the electric connections which require a careful sealing and fastening.
A further objective of the present invention is therefore to realize an assembly with unlimited operational liability, small and short dimensions as well as low noise level which can be tested with regard to function independently from the input or output unit.
The present invention provides a supporting housing between the bearing of the input or output end of the shaft and the pump housing which fixes the pump bearing sliding on the shaft in a blind-end bore of the supporting housing and accommodates a main bearing on the shaft spaced from the pump bearing so that the force flows between the shaft bearing in the pump housing and the electric motor housing.
It is known that in order to fasten the main bearing securely in the pump housing, very small fitting tolerances must be observed leading to different mounting forces. A further disadvantage is that the fastening aids for the exact positioning of the main bearing in the housing are missing, which are needed for observing the necessary mounting depth of the shaft in the pump housing.
A further objective of the present invention is therefore to develop an electric motor in such a way that the shaft can be supported in a precise manner and is easy to regulate and to mount, by evading the disadvantages mentioned above.
This objective is achieved by providing the bearing plate with an opening the inner diameter of which is smaller than the outer diameter of the main bearing, the bearing plate being arranged between the main bearing and the housing of the electric motor.
A further objective of the present invention is to improve an electric motor in such a way that, by simple means, a low-noise assembly can be realized which has unlimited operational reliability as well as small and short dimensions.
This objective is achieved by providing that the shaft end opposite to the input or output end rotates free from bearing forces, the input or output end of the shaft being supported in the pump housing and mounting a supporting plate (bearing plate) being clamped between the electric motor and the pump housing.